Search Results (59)

Recent comprehensive research (2023–2024) on basalt fiber-reinforced composites (BFRCs) has meticulously documented significant progress across diverse applications, including protective coatings, high-performance concrete, reinforcement bars, and advanced laminates. The central theme of these developments revolves around innovative composite design strategies that strategically incorporate basalt fibers to markedly enhance mechanical properties, durability, and protective capabilities against environmental challenges. Key advancements in synthesis methodologies highlight that the integration of BFs substantially improves abrasion and corrosion resistance, effectively inhibits crack propagation through superior fiber-matrix bonding, and confers exceptional thermal stability, with composites maintaining structural integrity at temperatures of 600–700 °C and demonstrating short-term resistance exceeding 900 °C. The underlying mechanisms for this enhanced performance are attributed to both chemical modifications—such as the application of silane-based coupling agents which improve interfacial adhesion—and physical–mechanical interlocking between the fibers and the matrix. These interactions facilitate efficient stress transfer, leading to a breakthrough in the overall multifunctional performance of the composites. Despite these promising results, the field continues to grapple with challenges, particularly concerning the long-term durability under sustained loads and harsh environments, and a notable lack of standardized global testing protocols hinders direct comparison and widespread certification. This review distinguishes itself by offering a critical synthesis of the latest findings, underscoring the immense application potential of BFRCs in critical sectors such as civil engineering for seismic retrofitting and structural strengthening, the automotive industry for lightweight yet robust components, and advanced passive fireproofing systems. Furthermore, it emphasizes the growing, innovative role of simulation techniques like finite element analysis (FEA) in predicting and optimizing the performance and design of these composites, thereby providing a robust scientific foundation for developing the next generation of high-performance, sustainable structural components. Full article

FeCoNiCrAl and FeCoNiCrAlScY high-entropy coatings were fabricated via electron beam physical vapor deposition. The microstructure and short-term isothermal oxidation behavior of the coatings were compared. Sc and Y inhibited coating element diffusion to the superalloy substrate and formed co-precipitated phases during coating manufacturing. The Sc/Y co-doped coating exhibited accelerated phase transformation from θ- to α-Al₂O₃ as compared to the undoped one. The effect mechanism associated with the nucleation of α-Al₂O₃ was discussed. The preferential formation of Sc/Y-rich oxides promoted the nucleation of α-Al₂O₃ beneath them, and the θ-α phase evolution process was directly skipped, which suppressed the rapid growth of θ-Al₂O₃ and the initial formation of cracks in the alumina film and provided the FeCoNiCrAl high-entropy coating with an improved oxidation property in the early oxidation stage. Full article

This study presents a simulation-based damage modeling and fatigue risk assessment of a reusable ceramic matrix composite thruster designed for short-duration, green bipropellant propulsion systems. The thruster is constructed from a fiber-reinforced ultra-high temperature ceramic matrix composite composed of zirconium diboride, silicon carbide, and carbon fibers. Time-resolved thermal and structural simulations are conducted on a validated thruster geometry to characterize the severity of early-stage thermal shock, stress buildup, and potential degradation pathways. Unlike traditional fatigue studies that rely on empirical fatigue constants or Paris-law-based crack-growth models, this work introduces a simulation-derived stress-margin envelope methodology that incorporates ±20% variability in temperature-dependent material strength, offering a physically grounded yet conservative risk estimate. From this, a normalized risk index is derived to evaluate the likelihood of damage initiation in critical regions over the 0–10 s firing window. The results indicate that the convergent throat region experiences a peak thermal gradient rate of approximately 380 K/s, with the normalized thermal shock index exceeding 43. Stress margins in this region collapse by 2.3 s, while margin loss in the flange curvature appears near 8 s. These findings are mapped into green, yellow, and red risk bands to classify operational safety zones. All the results assume no active cooling, representing conservative operating limits. If regenerative or ablative cooling is implemented, these margins would improve significantly. The framework established here enables a transparent, reproducible methodology for evaluating lifetime safety in ceramic propulsion nozzles and serves as a foundational tool for fatigue-resilient component design in green space engines. Full article

Rolling bearings are indispensable but also the most fault-prone components of rotating machinery, typically used in fields such as industrial aircraft, production workshops, and manufacturing. They encounter diverse mechanical stresses, such as vibration and friction during operation, which may lead to wear and fatigue cracks. From this standpoint, the present study combined a 1-D convolutional neural network (1-D CNN) with a long short-term memory (LSTM) algorithm for classifying different ball-bearing health conditions. A physics-guided method that adopts fault characteristics frequencies was used to calculate an optimal input size (sample length). Moreover, grid search was utilized to optimize (1) the number of epochs, (2) batch size, and (3) dropout ratio and further enhance the efficacy of the proposed 1-D CNN-LSTM network. Therefore, an attempt was made to reduce epistemic uncertainty that arises due to not knowing the best possible hyper-parameter configuration. Ultimately, the effectiveness of the physics-guided optimized 1-D CNN-LSTM was tested by comparing its performance with other state-of-the-art models. The findings revealed that the average accuracies could be enhanced by up to 20.717% with the help of the proposed approach after testing it on two benchmark datasets. Full article

This study investigated the deformation characteristics and mechanisms of the Baiyansizu landslide under the coupled effects of crack development, rainfall infiltration, and road loading. Numerical simulations were performed using GeoStudio software (Version 2018; Seequent, 2018) to analyze geological factors and external disturbances affecting landslide deformation and seepage dynamics. Four additional landslides (Tanjiawan, Bazimen, Tudiling, and Chengnan) were selected as comparative cases to investigate differences in deformation characteristics and mechanisms across these cases. The results demonstrate that rear-edge deformation of the Baiyansizu landslide was predominantly governed by rainfall patterns, with effective rainfall exhibiting a dual regulatory mechanism: long-term rainfall reduced shear strength through sustained infiltration-induced progressive creep, whereas short-term rainstorms generated step-like deformation via transient pore water pressure amplification. GeoStudio simulations further revealed multi-physics coupling mechanisms and nonlinear stability evolution controls. These findings highlight that rear-edge fissures substantially amplify rainfall infiltration efficiency, thereby establishing these features as the predominant deformation determinant. Road loading was observed to accelerate shallow landslide deformation, with stability coefficient threshold values triggering accelerated creep phases when thresholds were exceeded. Through comparative analysis of five typical landslide cases, it was demonstrated that interactions between geological factors and external disturbances resulted in distinct deformation characteristics and mechanisms. Variations in landslide thickness, crack evolution, road loading magnitudes, and rainfall infiltration characteristics were identified as critical factors influencing deformation patterns. This research provides significant empirical insights and theoretical frameworks for landslide monitoring and early warning system development. Full article

Carbon nanotubes (CNTs) exhibit high strength and high modulus, excellent electrical and thermal conductivity, good chemical stability, and unique electronic and optical properties. These characteristics make them a one-dimensional nanomaterial with extensive potential applications in fields such as composite materials, electronic devices, energy, aerospace, and medical technology. Cement-based materials are the most widely used and extensively applied construction materials. However, these materials have disadvantages such as low tensile strength, brittleness, porosity, shrinkage, and cracking. In order to compensate for these shortcomings, in recent years, relevant scholars have proposed to integrate CNTs into cement-based materials. Incorporating CNTs into cement-based materials not only enhances the microstructure of these materials but also improves their mechanical, electrical, and durability properties. The characteristics and fabrication process of CNTs are reviewed in this paper. The different effects of CNTs on the physical properties and hydration properties of cement-based materials due to the design parameters, dispersion methods, and temperature were analyzed. The results show that the compressive and flexural strength of CNT cement-based materials with 0.02% content increased by 9.33% and 10.18% from 3 d to 28 d. In terms of reducing the shrinkage and carbonization resistance of the cement base, there is an optimal amount of carbon nanotubes. The addition of dispersed carbon nanotubes reduces the resistivity, and the nucleation of carbon nanotubes promotes the hydration reaction. In general, under the optimal dosage, carbon nanotubes with uniform dispersion and short length–diameter ratio have a significant effect on the cement-based lifting effect. In the future, CNT cement-based materials will develop high strength, multifunctionality, and low cost, realizing intelligent self-sensing and self-repair and promoting green and low-carbon manufacturing. Breakthroughs in decentralized technology and large-scale applications are key, and they are expected to help sustainable civil engineering with intelligent infrastructure. Full article

One of the most significant challenges for 3D printing of construction elements from cementitious materials is the control of cracking caused by various contraction–shrinkage mechanisms, such as drying, chemical, plastic and autogenous shrinkage. This study addresses the effects of incorporating fine aggregates (maximum size ≤ 1.18 mm), both natural and recycled, as well as short (6 mm long) polypropylene (PP) fibres on the control of cracking in cementitious mixtures based on Portland cement. Admixtures and/or mineral additions (modifiers), such as metakaolin, micro-silica, calcium carbonate, and fine powders obtained from construction and demolition wastes were used in the mixtures. Mini-slump, flow rate and buildability tests were used to characterize the mixtures in their fresh state. Extrudability was evaluated using laboratory-scale 3D printing tests conducted with a plunger–piston extrusion system. It was demonstrated that the physical characteristics of the aggregates directly influence the extrusion capacity. Mixtures containing natural aggregates exhibited greater fluidity and lower water demand than those containing recycled aggregates. The results indicated that the maximum allowable volume of fibres was 0.75%. To evaluate the cracking susceptibility of the mixtures, both with and without reinforcement, hollow beams composed of seven layers were printed, and subsequently the elements were exposed to the outdoor natural environment and inspected for a period of 90 days. The inclusion of the PP fibres effectively prevented the occurrence of fissures and/or cracks associated with shrinkage phenomena throughout the inspection period, unlike in unreinforced mixtures, which cracked after 14 days of exposure to the environment. Full article

The fatigue behavior of metal specimens is influenced by defects, material properties, and loading. This study aims to establish a multi-scale fatigue crack growth model that describes physically short crack (PSC) and long crack (LC) behavior. The model allows the calculation of crack growth rates for uniaxial loading at different stress ratios based on the material properties and specimen geometry. Furthermore, the model integrates the Gaussian distribution theory to consider material heterogeneity and the experimental measurement errors that cause fatigue scatter. The crack growth rate and fatigue life of metal specimens with different notch geometry were predicted. The curves generated by the multi-scale model were mainly consistent with the test data from the published literature at the PSC and LC stages. Full article

Eggs are a highly nutritious food; however, those are also fragile and susceptible to cracks, which can lead to bacterial contamination and economic losses. Traditional methods for detecting cracks, particularly in processed eggs, often fall short due to changes in the eggs’ physical properties during processing. This study was aimed at developing a novel device for detecting egg cracks using electric discharge phenomena. The system was designed to apply a high-voltage electric field to the eggs, where sparks were generated at crack locations due to the differences in electrical conductivity between the insulative eggshell and the more conductive inner membrane exposed by the cracks. The detection apparatus consisted of a custom-built high-voltage power supply, flexible electrode pins, and a rotation mechanism to ensure a complete 360-degree inspection of each egg. Numerical simulations were performed to analyze the distribution of the electric field and charge density, confirming the method’s validity. The results demonstrated that this system could efficiently detect cracks in both raw and processed eggs, overcoming the limitations of existing detection technologies. The proposed method offers high precision, reliability, and the potential for broader application in the inspection of various poultry products, representing a significant advancement in food safety and quality control. Full article

To comprehensively understand the impact of various environmental factors on the self-healing process of graphene-modified asphalt, this study employs molecular dynamics simulation methods to investigate the effects of aging degree (unaged, short-term aged, long-term aged), asphalt type (base asphalt, graphene-modified asphalt), healing temperature (20 °C, 25 °C, 30 °C), and damage degree (5 Å, 10 Å, 15 Å) on the self-healing performance of asphalt. The validity of the established asphalt molecular models was verified based on four physical quantities: density, radial distribution function analysis, glass transition temperature, and cohesive energy density. The simulated healing time for the asphalt crack model was set to 200 ps. The following conclusions were drawn based on the changes in density, mean square displacement, and diffusion coefficient during the simulated healing process under different influencing factors: Dehydrogenation and oxidation of asphalt molecules during the aging process hinder molecular migration within the asphalt crack model, resulting in poorer self-healing performance. As the service life increases, the decline in the healing performance of graphene-modified asphalt is slower than that of base asphalt, indicating that graphene-modified asphalt has stronger anti-aging properties. When the vacuum layer in the asphalt crack model is small, the changes in the diffusion coefficient are less pronounced. As the crack width increases, the influence of various factors on the diffusion coefficient of the asphalt crack model becomes more significant. When the crack width is large, the self-healing effect of asphalt is more dependent on these influencing factors. Damage degree and oxidative aging have a more significant impact on the healing ability of graphene-modified asphalt than healing temperature. Full article

The retrofitting process contributes to the sustainability of the construction sector, since adopting measures to increase the lifespan of buildings reduces the need for new constructions. However, many of the materials used in this process come from nonrenewable sources and require significant water and energy consumption for production. The aim of this study is to assess the viability of using a more environmentally friendly mortar coating reinforced with short jute fibers (SJFRM) to reinforce ceramic brick masonry walls. Both coated and uncoated prisms were subjected to compression and flexural tests under two-point (line) out-of-plane loading. The reinforcement layer comprised mortar without fibers and mortars reinforced with jute fibers at levels of 2% and 4%, with lengths of 20 mm and 40 mm. Physical and mechanical tests were conducted to evaluate the properties of SJFRM in both fresh and hardened states. Results indicate that the compressive and flexural strengths were enhanced with SJFRM reinforcement due to alterations in the failure mode of the prisms. The fibers impede crack propagation in the reinforcement layer, enabling better redistribution of internal stresses in the prisms. This results in an increase of 6 to 9 times in stiffness under direct compression and up to 42 times in toughness under flexion in the prisms reinforced with SJFRM when compared to uncoated prisms. Full article

Stress relaxation cracking (SRC) is considered one of the major failure mechanisms for 347H stainless steel welds at elevated service temperatures or during post weld heat treatment (PWHT), especially within the heat-affected zone (HAZ). This work focuses on the characterization of SRC susceptibility within 347H physically simulated arc welded HAZ at elevated temperatures. A four-step SRC thermomechanical test in combination with finite element modeling (FEM) of the welding and testing processes is developed to establish a susceptibility map for HAZ. The test first runs a thermal cycle with three different peak temperatures (1335, 1275, and 1150 °C) to duplicate representative HAZ subzone microstructures, followed by time-to-failure examination under a variety of pre-stress (260–600 MPa) and pre-strain conditions (0.03–0.19) as a function of reheat temperatures between 750 and 1050 °C. With the aid of FEM, SRC susceptibility maps are generated to identify the threshold stress, plastic strain, and creep strain as a function of test temperature. It was found out that HAZ subzone with a lower peak temperature (1150 °C) appears to be slightly less susceptible to SRC than the other two subzones that experienced higher peak temperatures. Generally, time-to-fracture reduces with increasing initially applied stress and strain for all test temperatures. The pre-stress thresholds decrease from about 500 to 330 MPa as the testing temperature increases from 800 to 1050 °C, while the corresponding initial plastic strain thresholds reduces from 0.15 to 0.06. The SRC susceptibility was also evaluated through the Larson–Miller Parameter (LMP) analysis as a function of plastic strain, initial stress and starting stress upon reaching the testing temperature, respectively. The 1050 °C test with a high pre-applied strain (0.1) exhibits an extremely short time to failure (t = 3 s) that lies outside the general trend in LMP analysis. Additionally, it was identified that a plastic strain above 0.07 is identified to significantly reduce the bulk creep strain tolerance to fracture and therefore increases SRC susceptibility. Hardness measurement and fractography analysis indicated that the strain aging of niobium carbonitrides and other potential phases in conjunction with intergranular precipitates contributes to an increase in microhardness and increased intergranular cracking susceptibility. Full article

A new UHPC pre-stress transfer device is proposed for pre-stressed anti-floating anchor rods. To investigate the axial compression performance of the device during pre-stressing, physical experiments and a finite element verification were conducted on four different types of full-scale device specimens. The changes in the axial displacements and ultimate bearing capacities under axial pressure for the different types of devices were analyzed. The results indicated that bending failures occurred in the upper plate portions of all the types of specimens, with transverse cracks appearing near the upper plate portions of the short columns. The axial compression ultimate bearing capacity of each specimen exceeded the design value. Among them, the axial compression ultimate bearing capacity of the HM18 device increased the most relative to its design value by 87%, while axial compression ultimate bearing capacity of the HM45 device increased the least relative to its design value by only 2%. The new UHPC transfer device exhibits good applicability in pre-stressed anti-floating anchor rods. Full article

The quantity of different plastics generated after consumption is an impact factor affecting the environment, and the lack of recycling generates solid waste. The purpose of this work is to incorporate high-density recycled polyethylene fibers (HDPE) for possible use as concrete reinforcement. Physical and mechanical properties from recycled fibers were analyzed, such as density, absorption, and stress resistance, as well as workability, air content, porosity, concrete compression, and flexural strength properties. Samples were prepared with a low fiber content of 0.2% and 0.4%, as a substitution for sand weight, and lengths of 10 and 30 mm. To study corrosion phenomena, the specimens were exposed to a saline environment containing 3% sodium chloride for 365 days, and the electrochemical techniques including half-cell potential (HCP), electrochemical noise (EN), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were applied. The results showed a 4.8% increase in compressive strength with a low fiber percentage and short geometries, while flexural strength increased marginally by 2.3% with small quantities of HDPE fibers. All these factors contribute to greater material durability, less permeability, and crack control. A positive effect of fibers with short dimensions on the corrosion processes of a steel bar was observed, with the fibers acting as a physical barrier against the diffusion of chloride ions. Full article

The modifying effects of polymer on bitumen low-temperature performance are substantially compromised by the thermal breakdown of styrene–butadiene rubber (SBR) polymer during bitumen mixture production operations. The efficacy of the utilization of Sasobit/waste cooking oil (Sasobit/WCO) as a warm-mix additive has been demonstrated in mitigating the adverse consequences of thermal aging on SBR-modified bitumen binder (SB) while preserving the binder’s original performance characteristics. However, few studies have been conducted to further investigate the rheological properties and aging resistance of SB modified with Sasobit/WCO compounds. In this work, three additives—Sasobit, WCO, and Sasobit/WCO composite—were selected, and their effects on the physical and rheological characteristics of SB as well as the temperatures at which the mixtures were prepared were assessed. In addition, by using dynamic shear rheometers (DSR) and bending beam rheometers (BBR), the effects of this innovative warm-mix addition on the performance grade (PG) and aging resistances of SB were evaluated. According to the results, Sasobit/WCO composites outperform Sasobit and WCO in lowering the mixture preparation temperature. Sasobit/WCO also improves both the high- and low-temperature performance of SB simultaneously. Compared to hot-mix asphalt mixtures, the addition of Sasobit/WCO reduces the preparation temperature of the bitumen mixtures by 19 °C, which in turn helps to minimize the negative effects of temperature aging on the functioning of the SB. Additionally, the Sasobit/WCO composite addition can improve the SB mixture’s resistance to thermal cracking. After the introduction of Sasobit/WCO, the high-temperature PG of SB was raised by two levels, regardless of whether the warm-mix impact was taken into account. With the addition of Sasobit/WCO, SB’s resilience to short-term aging was enhanced. Full article